1. Field of the Invention
The present invention relates to a method of controlling the drying air temperature of a photosensitive material drying apparatus for drying a photosensitive material processed by processing solutions.
2. Description of the Related Art
In recent years, there has been a growing demand for high-quality and speedy processing of such photosensitive materials as graphic arts photosensitive materials, photosensitive materials for scanners, and photosensitive materials for X-ray films. These photosensitive materials are automatically processed by an automatic developing apparatus by using processing solutions such as a developing solution, a fixing solution, washing water, and the like, and are then dried.
In a drying section of this automatic developing apparatus, outside air which is introduced from outside the processor is heated by a heater. This heated warm air is blown onto the photosensitive material.
Since the photosensitive material is dried while being transported through the drying section at a predetermined speed, the drying of the photosensitive material must be completed within a predetermined time during which the photosensitive material passes through the drying section (i.e., transport distance/transport speed), and the temperature of the heater is set accordingly.
However, in a case where the amount of the photosensitive material dry processed per unit time increases, the humidity in the drying section becomes high over time and the drying conditions change, causing a decline in drying capability. Hence, it is effective, for example, to increase the drying capability by setting the heater temperature to a high level so as to increase the temperature within the drying section. However, if dry processing is continued while maintaining the heater temperature at the high level merely to secure the drying capability irrespective of this change in the drying conditions, when the amount of dry processing is small, the photosensitive material may possibly become overdried, and become curled or reduced in size to such an extent that the dimensions of the photosensitive material are not restorable.
To overcome this problem, if the heater temperature is set to a low value (i.e., a value close to a lower limit in securing the drying capability), the overdrying of the photosensitive material can be prevented.
Nevertheless, if the heater temperature is set to a low value, when the amount of dry processing is large, drying is conversely completed in a state in which the photosensitive material is underdried, so that strips of photosensitive material which are discharged consecutively from the automatic developing apparatus can possibly adhere to each other. Also, it is conceivable to change the set temperature of drying air in correspondence with the amount of processing in the drying section. However, there are cases where the temperature of the warm air fluctuates by large degrees to high and low levels owing to the relationship with the on-off control of the heater for maintaining the drying air temperature to a set level, thereby causing unevenness in drying.
Furthermore, since the state of drying the photosensitive material is affected by the water content prior to drying and the environmental conditions in which the processor is installed (particularly the absolute humidity), it is very difficult to maintain the state of drying the photosensitive material in a fixed state.